单项选择题
A．but B．if C．nearly D．fortunately
A．To outline contrasting types of economy. B．To explain the science of economics. C．To argue for the superiority of one economics. D．To compare barter and money exchange markets.
A．To tell campus personnel of the new library services. B．To announce the new movies on campus this summer. C．To notify university people of important schedule changes. D．To remind students to validate (使生效) their identification cards.